ML20196C409

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Safety Evaluation Supporting Amends 238 & 228 to Licenses DPR-77 & DPR-79,respectively
ML20196C409
Person / Time
Site: Sequoyah  Tennessee Valley Authority icon.png
Issue date: 11/19/1998
From:
NRC (Affiliation Not Assigned)
To:
Shared Package
ML20196C380 List:
References
NUDOCS 9812020047
Download: ML20196C409 (3)


Text

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UNITED STATES O

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NUCLEAR REGULATORY COMMISSION o

WASHINGTON, D.C. 2006H001 SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO AMENDMENT NO.238 TO FACILITY OPERATING LICENSE NO. DPR-77 AND AMENDMENT NO 228 TO FACILITY OPERATING LICENSE NO. DPR-79 TENNESSEE VALLEY AUTHORITY SEQUOYAH NUCLEAR PLANT. UNITS 1 AND 2 DOCKET NOS. 50-327 AND 50-328

1.0 INTRODUCTION

The Tennessee Valley Authority (TVA, the licensee) requested amendments to Operating Licenses DPR-77 and DPR-79 for Sequoyah Nuclear Plant (SON), Units 1 and 2, respectively, in a letter to the U.S. Nuclear Regulatory Commission (NRC) dated August 21,1996. The amendments would revise the SON Units 1 and 2 Technical Specifications (TS) to extend the applicability of the limiting condition of operation (LCO) for the condensate storage tank (CST) to Mode 4 when the steam generators are relied upon for heat removal. The licensee also proposed changes to associated action statements, surveillance requirements (SR), and TS bases.

2.0 BACKGROUND

in 1995, by license Amendment Nos. 206 and 196 for Units 1 and 2, respectively, the licensee revised TS 3.7.1.2, Auxiliary Feedwater System, to be consistent with the Westinghouse Standard Technical Specifications contained in NUREG-1431. This change expanded the mode applicability for the auxiliary feedwater (AFW) system's LCO from Modes 1,2, and 3, to include " MODE 4 when steam generator is relied upon for heat removal." At that time, the licensee did not recognize the need for a change to the mode of applicability for the CST which provides the water source for the AFW pumps. Presently, TS 3.7.1.3 requires the CST to be operable in Modes 1,2, and 3. This is not consistent with the TS required AFW operability in Mode 4. As an interim corrective action, the licensee is currently operating with administrative controls to ensure that CST is operable in all applicable modes when the AFW system is required to remain operable. The licensee has now proposed appropriate TS changes to correct the disparity between the CST and AFW TS.

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TVA proposes to modify TS 3.7.1.3, " Condensate Storage Tank" to:

(a) extend the mode of applicability to include " MODE 4 when steam generator is relied upon for heat removal." Current modes of applicability are Modes 1,2, and 3.

(b) revise Action (a) to increase the allowable action time for achieving hot shutdown to 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> from the current 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br />, and to add the phrase "without reliance on steam 4'

generator for heat removal"to be consistent with the language in NUREG-1431.

(c) revise Action (b) to modify the phrase " Demonstrate the operability Essential Raw Cooling Water System as a backup supply to the auxiliary feedwater pumps.." to " Verify by administrative means operability of the Essential Raw Cooling Water System (ERCW) as a backup supply to the auxiliary feedwater pumps..." to be consistent with the language in 1

NUREG-1431.

(d) add the phrase "without reliance on steam generator for heat removal" to Action (b) to be consistent with the language in NUREG-1431.

l (e) delete the current SR 4.7.1.3.2 for verifying ER,CW operability every 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> and make the requirement a footnote to Action (b) instead.

(f) revise TS Bases 3/4.3.2 to provide guidance concerning the AFW suction pressure-low function as to the modes when this function is required to be operable.

(g) correct a typographical error in Action (b) by replacing "pmps" with " pumps."

j 3.0 EVALUATION Following a reactor trip, decay heat is dissipated by evaporating water in the steam generators and venting the steam either to the condensers or to the atmosphere. In such situations, steam generator water inventory must be maintained at a level sufficient to ensure adequate heat i

transfer and decay heat removal. The AFW system pumps deliver this emergency water supply to the steam generators. The AFW system provides emergency water to the steam generators until either normal feed water flow is established or the residual heat removal (RHR) system can assume the decay heat removal function. The primary sources of water for the AFW system pumps are the condensate storage tanks. On low suction pressure, the AFW pumps are designed to automatically swap to the ERCW system.

l SQN has two CSTs (one for each unit) that provide cooling water to the suction of the AFW pumps. TVA's proposed change to extend the mode of applicability for the CST to " MODE 4 i

when steam generator is relied upon for heat removal" would ensure that a source of water is available to the required AFW train until the RHR system can assume the decay heat removal function. This change is consistent with the mode requirements for AFW operability.

Therefore, the staff finds the proposed change to the CST operability acceptable.

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Adding the phrase "without reliance on steam generator for heat removal" to current Actions (a) and (b) would be done for the pupoce of ensuring unit cooldown to RHR entry conditions without reliance on steam generators. The staff notes that this phase is consistent with the language in Section 3.7.6 of NUREG-1431 and is discussed in Bases Section B 3.7.6. The staff finds the proposed change to be consistent with the proposed mode of applicability for the CST and is, therefore, acceptable. The staff also finds the action time for achieving hot standby from 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> to 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> is reasonable for transition from the steam generator mode of decay heat removal to RHR entry conditions and would achieve the required plant condition in an orderly manner without challenging other plant systems.

SR 4.7.1.3.2 for demonstrating operability of the ERCW system is redundant to TS 3.7.4 which requires two ERCW loops to be operable in Modes 1,2,3, and 4. SR 4.7.1.3.2 for demonstrating operability of the ERCW system is, therefore, not necessary and the staff finds deleting SR 4.7.1.3.2 to be acceptable.

The staff also finds the proposed TS changes discussed in items (c), (e), and (g) above to be editorial and, therefore, acceptable.

4.0 STATE CONSULTATION

in accordance with the Commission's regulations, the Tennessee State official was notified of the proposed issuance of the amendments. The State official had no comments.

5.0 ENVIRONMENTAL CONSIDERATION

The amendment changes a requirement with respect to installation or use of a facility component located within the restricted area as defined in 10 CFR Part 20 and changes surveillance requirements. The NRC staff has determined that the amendment involves no significant increase in the amounts, and no significant change in the types, of any effluents that may be released offsite, and that there is no significant increase in individual or cumulative occupational radiation exposure. The Commission has previously issued a proposed finding that the amendment involves no significant hazards consideration, and there has been no public comment on such finding (61 FR 52967, dated October 9,1996). Accordingly, the amendments meet the eligibility criteria for categorical exclusion set forth in 10 CFR 51.22(c)(9). Pursuant to 10 CFR 51.22(b), no environmental impact statement or environmental assessment need be prepared in connection with the issuance of the amendments.

6.0 CONCLUSION

The Commission has concluded, based on the considerations discussed above, that: (1) there is reasonable assurance that the health and safety of the public will not be endangered by operation in the proposed manner, (2) such activities will be conducted in compliance with the Commission's regulations, and (3) the issuance of the amendment will not be inimical to the common defense and security or to the health and safety af the public Principal Contributor: L. Raghavan, NRR Date: tbveter 19, 1998 l

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